This invention generally relates to electronic musical instruments and particularly to an electronic keyboard instrument having a function of touch response for controlling a tone based on the detected touch of the key.
The prior art electronic keyboard instrument has used a key state sensor in the form of one or more contact switches disposed in relation to each key of the keyboard. These contact switches are arranged so as to change their states at two different positions of the key. When the key is depressed, the key will pass by a first predetermined displacement, changing the switch to another state, and then pass by a second predetermined displacement, causing further change of the switch state. An initial touch measuring apparatus connected to the contact switch measures the time for the key to move from the first displacement to the second. The measured time is, of course, in inverse proportion to the depressing velocity of the key. This information is utilized to control a tone, thus providing a touch response.
It is noted, however, that the time of moving between predetermined key displacements, as extracted by the prior art, is the sole variable factor that varies depending on the key operation. This indicates that the touch response provided by the prior art is insufficient and leaves room for improvement.